Subject: Re: [linux-audio-user] unwanted noise in soundcard
From: dplist_AT_free.fr
Date: Sat Aug 31 2002 - 20:35:26 EEST
On Mon, 26 Aug 2002 09:19:03 +0100
Steve Harris <S.W.Harris_AT_ecs.soton.ac.uk> wrote:
> On Mon, Aug 26, 2002 at 03:48:25 +0200, dplist_AT_free.fr wrote:
> > I own a M-Audio Delta 66 + Omni I/O (breakout + preamp box) that I
> > use with alsa-drivers-0.9rc3. jackd, ardour, envy24control seem to
> > work fine but I can hear unwanted noise in both left and right
> > monitoring channels. The noise is sometimes very present, sometimes
> > less
>
> It could be a ground loop. Could you put a recording of the noise up
> somewhere? I've had this problem when using a laptop plugged into the
> mains with a projector and mixer on different mains circuits.
Steve,
Sorry for replying so late, I haven't been able to find time
until now. I've put a recording of that bad noise on :
http://dplist.free.fr/mono.ogg
or the bigger http://dplist.free.fr/mono.wav
The noise in the file is louder than normal because it has been
amplified through my beakout box preamp, but it doesn't matter much
anyway.
Do you think it could be caused by a PC hardware problem (pci bus ?) ?
by a kernel problem ? by the alsa driver ? by the sound card itself ?
(in that case I'll have to return it).
Thanks a lot for giving me your opinion on this.
> For me most of the noise appeared to come from the cdrom drive (it was
> intime with the flashing light), but it was the ground loop that
> caused the problem. Unplugging the laptop from the mains fixed it -
> not that that really helps here.
>
> I've also had nightmare ground loops at a gig, triggered by a MIDI
> chain - I solved that with a di box IIRC.
>
> Check how your monitor, mixer and pc are grounded. There is some
> advice about fixing problems here:
> http://www.sospubs.co.uk/sos/1994_articles/aug94/groundloops.html
Thanks for the pointer. I don't think I'm experiencing a ground
loop though, given the type of noise I hear. It sounds like "digital"
noise to me.
Thanks again and have a nice day.
> - Steve
-- David
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